Lighting systems such as liquid crystal display (LCD) backlights sometimes comprise red, green and blue (RGB) light-emitting diodes (LEDs). Together, the RGB LEDs can be used to produce a mixed light (e.g., a white light in the case of an LCD backlight).
System manufacturing variations, operating conditions, LED aging, and other factors can cause the intensity and color of individual ones of a lighting system's LEDs to drift. As a result, an optical feedback system employing one or more photosensors is often used to measure the intensity and/or color point of the mixed light produced by an LED lighting system. The feedback system's outputs are then used to regulate the drive signals, and thus the intensities, of individual ones or groups of the lighting system's LEDs.